1. Field of Invention
The present invention relates to a linkage device and a programmable control unit using the same.
2. Related Art
Programmable logic controllers (PLC) are electronic operation control systems. The PLC uses the programmable memory to store the instructions for executing the functions such as logic, sequence, timing, counting and calculation. Besides, the PLC further uses the digital/analog input output module to control various machines or procedures.
Since the programmable controller has the advantages of simple operation, less manpower cost, and flexible in design, it has been widely applied to the industrial control automation. In practice, it is possible to use multiple programmable control units with different functions according to various requirements. The programmable control units can be optionally assembled or installed on a bottom board and a frame through their connecting ports, thereby forming an expandable programmable controller.
However, when the programmable control unit is assembled with the bottom board, the connecting port thereof must be aligned to and inserted into the corresponding connector of the bottom board. If the connecting port of the programmable control unit is touched, it is highly possible to affect the electrical reliability thereof, which may result in the short circuit or damage of the programmable control unit.
Therefore, it is an important subject of the invention to provide a linkage device and a programmable control unit using the same that can be easily and actually assembled and can avoid the undesired contact, which may affect the electrical properties. Accordingly, the invention can prevent the short circuit and damage of the programmable control unit during the assembling procedure, thereby increasing the reliability of the programmable control unit and decreasing the assembling cost for operators.